Environmental concerns for preventing leakage of fluorocarbon refrigerants to the atmosphere from the reinforced, high pressure rubber tubing presently used in motor vehicle air conditioning units has led to a necessity that more leakproof materials, such as metal tubing, be used. Unfortunately, one cannot simply substitute a length of formed metal tubing for rubber in this situation since the engine mounted compressor undergoes a continuous and a rather substantial amount of movement due both to engine operation and vibrations relative to the frame mounted components such as the condenser and evaporator. For example, the typical resilient mounting of an engine on the vehicle frame allows about 0.500" of total movement. The movement would very quickly induce stresses in the metal tubing which would cause fatigue failure. It is conventional to absorb vibration and other movements of a metal piping system by means of a vibration connector assembly containing a metal bellows and such an assembly having rubber for sound and vibration damping over the crests of the corrugations and a metal braid reinforcement is disclosed in Poxon et al U.S. Pat. No. 3,420,553. Furthermore, it is known that the flexibility and the ability of such a connector to resist fatigue failure is related to the thickness of the wall of the bellows and its length. The greater the thickness, the longer the bellows must be to resist vibrations of a given deflection. Where internal operating pressures in the order of about 300 psi must be resisted, as is the case in refrigerant lines, the bellows wall thickness must not be so thin that its corrugations will collapse. For example, it has been determined that a 0.020' wall thickness and a corrugated bellows length of 7 inches is adequate where a lateral deflection of 0.25 inch per connector is to be expected. To accommodate the lateral relative movement between a pair of members which are spaced from each other, it is desirable to utilize a pair of connectors which are positioned in the piping system with their axes generally normal to each other since the connectors can move laterally but cannot move axially due to the restraint of the braided sleeve.
In addition to the aforementioned Poxon et al patent disclosing the use of rubber-like materials for bellows damping, several other patents disclose the molding of rubber-like materials into bellows corrugations. These include Panagrossi U.S. Pat. No. 2,685,459, Donkle, Jr. U.S. Pat. No. 3,232,640 and Swedish Pat. No. 132,558. In no instance is the rubber disclosed as being used to permit the bellows wall to be reduced in thickness and length to a point where the fluid pressures normally expected in the bellows would cause the destruction of the bellows if the rubber were not present.